Conjugated linoleic acids (CLA) are naturally occurring geometric and positional isomers of linoleic acid, or octadecadienoic acid, produced naturally by microbes in the rumen of ruminant animals. Numerous therapeutic uses for CLA mixtures have been reported (see, e.g., U.S. Publ. No. 2005/0154059 and U.S. Pat. Nos. 6,395,782; 5,814,663; 5,760,082; and 5,585,400).
CLA contains two double bonds separated by a single bond in a cis-, trans-configuration that commonly occurs between the 8- and 13-carbon positions. The two most common isomers of CLA are trans-10, cis-12 and cis-9, trans-11. However, while most commercial synthetic CLA supplements contain an approximately equal amount of the trans-10, cis-12 and cis-9, trans-11 isomers (i.e., a 50:50 blend), the latter represents approximately 90-95% of the total CLA in rumenic food (i.e., dairy) products. Consequently, the cis-9, trans-11 isomer is commonly referred to as rumenic acid (RA).
Methods for making RA and rumenic acid-rich conjugated linoleic acid (RAR-CLA) have been reported (see, e.g., WO 2016/025312 and U.S. Pat. Nos. 8,614,074; 8,203,012; 6,897,327; 6,184,009; and 5,856,149). For instance, WO 2016/025312 describes a method in which a CLA-based triglyceride (Clarinol G-80, product of Stepan Lipid Nutrition) is selectively hydrolyzed using a lipase catalyst to give a mixture of unconverted triglycerides and a fatty acid mixture that is enriched in rumenic acid. The fatty acid mixture is separated by wiped-film evaporation from the less-volatile triglyceride component. The triglyceride component, which is enriched in the trans-10, cis-12 isomer, is also desirable as a therapeutic agent (see, e.g., U.S. Publ. No. 2013/0274336).
Rumenic acid has shown promise as an anti-inflammatory dietary supplement in humans. For example, L. Penedo et al. (J. Nutri. Biochem. 24 (2013) 2144) reported that 8 weeks of RA-enriched butter improved inflammatory markers in young, healthy men and women. A. Turpeinen et al. (Brit. J. Nutri. 100 (2008) 112) reported that 8 weeks of RA supplementation reduced the allergic responses mediated by inflammation in young men and women with birch pollen allergy. F. Sofi et al. (NMCD 20 (2010) 117) showed that 10 weeks of dietary supplementation with cheese naturally rich in RA (e.g., pecorino) reduced inflammation in middle-aged men and women. Therefore, despite limited applied studies in humans, existing evidence suggests that RA may have anti-inflammatory effects.
The mechanism of action for the anti-inflammatory effects of RA may be due to its actions as an agonist of peroxisome proliferator-activated receptor-γ (PPARγ). PPARγ is a ligand-activated transcription factor that regulates gene transcription. PPARγ is expressed in most tissues of the body and has important metabolic and inflammatory effects. A. Jaudszus et al. (Lipids Health Dis. 15 (2016) 1) demonstrated that RA reduced inflammatory responses in human epithelial cells via activation of PPARγ. Similarly, Y. Yu et al. (Biochim. Biophys. Acta, Mol. Cell Biol. Lipids 1581 (2002) 89) showed that RA activated PPARγ and served as an antioxidant in mouse macrophage cells. Therefore, investigators have suggested that RA may have therapeutic value in the management of conditions characterized by chronic inflammation such as atherosclerosis, asthma, inflammatory bowel disease, obesity, and aging.
Aging is also characterized by greater oxidative stress in tissues such as cartilage (H. Choi et al., Fitoterapia 86 (2013) 19 and R. Loeser, Osteoarthr. Cartilage 17 (2009) 971). N. Aryaeian et al. (Int. J. Rheum. Dis. 12 (2009) 20) studied the effects of a 50:50 isomeric blend of RA and trans-10, cis-12 CLA on symptoms of rheumatoid arthritis. The authors observed a decrease in disease activity, pain, and stiffness with CLA supplementation and hypothesized that these decreases were due to reduced inflammation suggesting that RA might have protective effects against age-related joint dysfunction and/or discomfort through anti-inflammatory and antioxidant effects. For further related studies, see Y. Chen et al., Mol. Neurobiol. 46 (2012) 114; M. Collino et al., Eur. J. Pharmacol. 530 (2006) 70; H. Fahmi et al., Mod. Rheumatol. 21 (2011) 1; R. Kapadia et al., Front. Biosci. 13 (2008) 1813; R. Loeser, supra; T. Matsui et al., J. Int. Med. Res. 35 (2007) 482; L. Penedo et al., supra; and A. Turpeinen et al., supra.
Although many studies have examined PPARγ's cellular effects and demonstrated RA's activity as a PPARγ agonist, few studies have examined the effects of RA on applied, functional outcomes in humans, including its impact on joint health in aging adults.